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Bill, Master Plumber
Category: Plumbing
Satisfied Customers: 262
Experience:  45 years in the plumbing trade, building So. Cal.w/NITC & LA CITY certification
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I have an old, 2-piece Kohler toilet that has a stealth leak.

Resolved Question:

I have an old, 2-piece Kohler toilet that has a stealth leak. I think it is in the overflow drain tube. I've replaced the flapper valve. When I fill the tank and then turn off the water supply, the tank slowly drains down to the top of the collar at the bottom of the drain tube. (The collar holds the lugs for the flapper valve.) Then the leak stops, leaving about an inch of water in the tank, which is enough to cover the flapper valve. So the flapper valve appears to be sealing. I checked the tube for cracks but can't find any. Could it be at the seal between the tube and collar?
Submitted: 5 years ago.
Category: Plumbing
Expert:  Bill replied 5 years ago.


Sou you have a new flapper. Try this clean the flush valve this is where the flapper seals and you have to make sure that it rest on the center of the flush valve.They make different sizes so you have to make sure you have the right one. One more thing adjust the chain and make sure it has enough slack to let it rest all the way down on the flush valve.

You can all so do a test hold down the flapper and see if the water still leaks.

And make sure the the line that goes in the over flow tube is not to far down in this tube it should just be in far enough in the holder to keep it in place.

The tube and collar are one piece so it should not leak there if it is leaking there then you will need a new one and they dont coast that much.


Customer: replied 5 years ago.
Answers didn't help me, since I had tried them all and the slow leak still happens. I've tried two new things: (1) The three hold-down screws on the bottom of the tank were a bit loose, so I tightened them. (2) While the new flapper is identical to the old one, I filed out a small piece of the hinge that sits on the two lugs on each side of the overflow tube, thinking that that would give the flapper a tighter fit. I am now testing the tank and will let you know results tomorrow.
Expert:  Bill replied 5 years ago.
Ok I will see what happens tomorrow.
Customer: replied 5 years ago.
OK, nothing stopped the leak so I pulled the tank and replaced everything inside it with genuine Kohler parts. Re-installed the tank and it still leaks into the toilet bowl!!! No leaks outside the tank, so I'm thinking I didn't seal the overflow drain well enough (but tightening the three bolts any more would probably have cracked the bowl) or the tank must have a hairline crack in it. Your thoughts?
Expert:  Bill replied 5 years ago.


Do you have this type of flapper

If so I would try this type of flapper

The bolts just tighten the tank to the bowl and keep the water from leaking onto the outside of the bowl when flushed. this has nothing to do with the water leaking into the bowl.

You see the nut in the photo above that tightens the flush valve to the tank if this is not tight then the water would only leak on the outside of the tank not inside the bowl.

So if you have a flapper with a float then I would try one without a float and you can not just take the float off you would need a new flapper.

If the tank had a hairline crack the water would be all over the place and not going into the bowl.


Customer: replied 5 years ago.
Sorry for the delay, but I was out of town. Tank still leaked into bowl, and completely drained out, so I decided the leak was in the seal to the overflow tube, not the flapper. I found the old rubber seal to see why it worked and the new one didn't. And to my surprise I found a flat fiber washer just inside the seal, which wasn't included in the package for the new seal. I installed the washer and was able to screw the plastic nut much tighter. Now the leak is almost---but not quite---gone. (I filled the tank, turned off the water supply and found that the water lever dropped about !/4 inch in 12 hours.) Should I tighten the plastic nut even more?
Expert:  Bill replied 5 years ago.


First off this is good news.

And you can tighten more but I would put some plumbers putty on.

To do this you would remove the overflow tube and put plumbers putty around the tube before you put it back through the tank then re tighten the nut and this should stop the leak.

Good luck.


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